[Nested melanoma]

Abstract

Background: Nested melanoma in elderly subjects is an entity that has been reported in the literature only since 2012. In this paper, we describe its distinctive clinical, dermatoscopic and histopathological features and compare them to previous published cases, with the aim of highlighting certain specific criteria of this melanoma subtype.

Case report: A 52-year-old man was referred for the presence on his chest of a large suspicious pigmented lesion of irregular shape and colour. Dermatoscopically, the lesion was chaotic and characterized by a black, structureless, eccentric area with some peripheral globules as well as some segmental radial lines. Histopathological examination revealed the presence of an asymmetric lesion with large junctional melanocytic nests showing a focal tendency to gathering and some cytological atypia. A diagnosis of nested melanoma was ultimately made.

Discussion: Nested melanoma of the elderly represents a distinct anatomoclinical variant of superficial spreading melanoma. Clinically, the lesion is usually large and occurs in photodamaged skin. We would stress that the "elderly" criterion is not mandatory given the numerous cases reported in people under 60 years. The main dermatoscopic feature is a globular pattern, but several features characteristic of superficial spreading melanoma may also be present. Histological diagnosis may be difficult because of the mainly nested pattern, and the condition may be confused histologically with a benign junctional nevus. But these large junctional nests of different sizes, with bridging and cytonuclear atypias, together with asymmetry of the lesions are the hallmark of this special kind of melanoma.

Keywords: CGH-array; CHG-array; Dermatoscopie; Dermatoscopy; FISH; Globular pattern; Hybridation génomique comparative; Hybridation in situ en fluorescence; Mélanome en thèques; Mélanome à extension superficielle; Nested melanoma; Patron globulaire; Superficial spreading melanoma.